A word from Kat, the 'Katana' costume creator:

I (Kat) made this costume for my little sister, Arwen, who wore it.
The idea for this Suicide Squad Katana costume came when I was making a Harley Quinn costume for myself. Arwen saw the costume and decided she wanted a Suicide Squad costume too. I looked at the character list again and, as I suspected would happen, found that Katana would be the best costume for Arwen, because she looks more like Katana than any other characters (aside from Harley Quinn). We probably would have done Katana anyway because we liked her costume. When we decided on Katana I started putting together the design for making it.
I didn't get to make as much of this costume as I wanted to because I've had a lot to do for school, but I tried to make as much of it as possible. Here is how I made/aquired each piece of the costume. The white shirt is just a white tank top we got from a store. We knew that in the original costume was a white crop top, but we didn't want to do a crop top, so we did the tank top. The Jacket started out as a black turtleneck. We couldn't find a black jacket but I figured it would work just as well to convert the turtleneck. "Convert" really just meant "cut a straight line down the front" though. Thankfully, we didn't have to hem anything because the turtleneck was made of fabric that doesn't fray. After I cut it, I was just left with a plain jacket, so I painted on the flowers with gold acrylic paint. Before painting them on I searched the internet for pictures of Katana's jacket until I was sure I knew exactly what it looked like. To paint them on, I scaled the flowers with the picture, then marked the ends of the flower petals and the radiai of the circles. I tried using masking tape to mark out the lines on the big flower, but gave up after a while because it was easier to freehand. I freehanded everything after that. Painting the jacket was fun, but it took a while. After I painted the jacket I moved on to the leggings. The leggings started out as a plain pair of black leggings. I painted the symbols on with the same paint as the flowers. It was difficult to find a good picture of the symbols, and I ended up using pieces of two pictures. It was also dificult to scale them. Once I figured out the scale I freehand painted them on. But before I painted them on, I painted the part of the leggings that would be behind them with black acrylic paint so it would look more like the movie costume. I used a few paintbrushes to paint them on because I wanted the symbols to look exactly the way they're supposed to. Now I'll move on to my favourite part of the costume, the mask. When I was figuring out how to put together the costume I knew that I wanted the mask to be able to stay on without being tied on. After researching ways to make masks and thinking about it, I decided on paper mache. Because I wanted the mask to stick to Arwen's face, I knew it had to be moulded to her face. Because of that I made the first layer of the mask by sticking the paper mache on her face and letting it dry. We forgot to put oil or vasaline on her eyebrows before I put the paper mache on her face though, so it stuck to her eyebrows when we tried to pull it off. Because it stuck, she lost a few eyebrow hairs when we pulled it off. We got a laugh out of it though! After I had the first layer, I covered it in an uncounted number of other layers of paper mache. When it was as hard as I wanted it, I covered it in a layer of paper towel paper mache to smooth it out, and moved on to painting the mask. To start with, I covered the mask in white acrylic paint. Then I figured out the scale of the red dot. To do the red dot in as perfect a circle as I could, I marked one out on paper, cut it out, and used it as a stencil on the mask. I marked it out with pencil then painted the outline with red, and filled it in. To finish, I painted black around the eyes with acrylic. Now I'll tell you about my least favourite part, the sword. I didn't like the sword because it didn't turn out the way I wanted. I made the hilt out of 6 tic tac boxes covered in duct tape. They were made in two rows of three. Between the two layers I put the end of the wire frame of the blade. The wire frame was very hard to get straight and scaled the way I wanted. Then I covered the wire frame in paper mache, in the shape I wanted the blade to be. After putting on more layers of paper mache until the blade wasn't flimsy and was the right thickness, I decided to move on to painting it. There was a problem with that though, I thought I had silver paint, but I didn't. I couldn't buy the paint so I ended up covering the blade in aluminum foil. After it got put on, the aluminum foil got wrinkled, as you can see in the picture. That's what I don't like about the sword. I think the only things I haven't written about yet are the shoes (I know there aren't any in the picture), the arm band (also not present in the pictures), and the red belt and straps. The belt and straps are made of a red satin fabric that I cut and folded into the right shape and size, and tied on for Arwen. She had shoes to wear with the costume, but like I did with my costume, forgot to put them on for pictures and didn't get another chance to take pictures. They were a pair of dark grey tennis shoes that matched the costume. She also had a band to put on her arm that was made of white fabric and had a dot like on her mask painted on it, but it was lost when we took pictures. I think that I've talked about all of the pieces now.
Something funny happened while I was working on the mask. I left it on the table overnight to dry, and when I checked on it in the morning, a chunk was missing out of it, and the whole thing was torn up. I got annoyed. Eventually though, I figured out what had happened. The cat had eaten part of it, and chewed on the rest. After that I kept the mask away from the cat. Thankfully I was able to repair it.